Just recently, my 2010 MBP (running El Capitan) won't go to sleep when left on its own -- it has to be put into sleep manually, and sometimes it will wake from sleep on its own. This has only been happening for a few weeks, and there were no major changes to the computer at that time. It's a fairly minor issue, but I'd still like to try and resolve it. If you have any suggestions as to what might help, I'd love to hear them. I tried resetting the SMC but it didn't seem to change anything. Another possibility is to upgrade to Sierra, but I feel like I shouldn't have to do that just to resolve this issue. Thanks in advance for any suggestions!